Linux Commands---echo, wall, write, clear, sync, uptime commands

EHCO command: Display a line of text

"Feature" will print out the content by default, which is most commonly used in the shell.

Syntax

echo option argument

"Common options"-E activates escape characters

\b: Delete the previous character \c: End with a newline symbol \ n: newline and the cursor moves only the beginning of the line \ r: The cursor moves to the beginning of the line, but does not wrap \ t: Insert tab\\: Insert "\" character

Instance

Print the given string directly [[email protected] tmp]# echo  "Hello word" hello word//add-e option to activate escape character "\ N "[[email protected] tmp]# echo -e " Hello\nword " helloword//Delete the previous character to add the" \b "escape character [[ email protected] tmp]# echo -e  "Hel\blo\nword" heloword//add newline "\ n" and tab means "\ t" [email  protected] tmp]# echo -e  "A\TB\TC\T\ND\TE\TF"  a        b       cd       e        f//Displays the shell environment where the current user is logged on [[Email protected] ~]# echo $0-bash View the previous command execution result status [[email protected] ~]# echo $?0//View the current user's home directory path [[email protected] ~ ]# echo  $HOME/root//Displays the SHELL environment and path [[email protected] ~]# echo  the current user is logged on $SHELL/bin/ bash//But the usual is echo a string to the file,[[email protected] ~]# echo  "www.baidu.com"  > /tmp/ B.txt | cat&nBsp;/tmp/b.txt 

Wall command: Send a message to everybody ' s terminal

"Feature" sends information to each end user

Syntax

Wall ' message '

"Instance" sends content "message" content to all user terminals, including itself, but requires online users

[Email protected] ~]# wall ' message ' [[email protected] ~]# broadcast message from [email protected] (PTS/2) (Fri Apr 22 0 5:44:54): Message

Write command: Send a message to another user

"Feature" sends information to other users,

Syntax

write [users] [TTY]

When you enter the Write users tty# enter the input mode, enter the content you need to enter, and then return to send information to each other, the other party can receive information.

Clear Command: Clear the terminal screen

"Function" clear terminal screen information, referred to as clear screen, shortcut key ctrl+l can be used to indicate the command line input.

Syntax

Clear or Ctrl+l

This command is available when there is too much content on the screen and needs to be re-cleaned, but it is not really clear, it is just the equivalent of a non-informational screen.

Sync Command: Flush file system buffers

"Feature" refreshes the file system's buffers, that is, writes the buffer's files to the hard disk

Syntax

Sync

Uptime Command: Tell how long the system has been running

"Features" show how long the system has been running so far, can see the information is: the current time, the system has been running for a long time, the user is currently logged into the system, the system in the past 1 minutes, 5 minutes, 15 minutes of the average load balance.

Syntax

Uptime

Instance

Add-V option displays version information [[email protected] ~]# UPTIME-VPROCPS version 3.2.8//default command using [[email protected] ~]# uptime 06:10:47 up 5:43 , 3 users, load average:0.01, 0.01, 0.00

This article is from the "Perthon" blog, make sure to keep this source http://perthon.blog.51cto.com/10484057/1766431

Linux Commands---echo, wall, write, clear, sync, uptime commands